The present invention relates to a laser output changing device capable of changing laser output with stability.
Recently, a laser is widely utilized in various fields.
In fields of medical and small scale machining application, there is used CO.sub.2 gas laser having an output of several tens of Watt or so as a typical laser. In such a gas laser it is necessary to change or vary the output derived from its oscillator according to usage.
Such a CO.sub.2 gas laser is used to oscillate with the excitation by glow discharge in low pressure mixed gas of several tens of torr or so, so that the output of the laser oscillator is made variable by changing the amount of discharge current. Such a changing means, however, has following disadvantages.
(a) Current control circuit of high voltage (few Kv to several tens of Kv) is required to control discharge current so that circuit elements for performing current control at such a high voltage become large in size and expensive.
(b) In the low pressure gas laser for discharge excitation such as CO.sub.2 gas laser the safety oscillating region of the laser is not always positioned at the discharge stabilizing region so that the change of discharge current causes lack of stabilization of discharge and thus laser oscillation. Therefore, it is desirable to fix the discharge current and voltage at most suitable value.
(c) Because of the reason of the above disadvantage (b) even by the control of discharge current the output of the laser can be changed with stability only at low output region being 30% or so of maximum output of the laser.
(d) Current control elements become a factor which determines durability of the device.
While the CW oscillation of high output laser having output higher than that of the above described laser, such as CO, HF, DF, or the like has the same problem so that the output of the high output laser must be changed according to application. In this case, however, suitable means for changing output of the laser has not been developed.